1. Field of the Invention.
This invention relates generally to hot water heating, and more particularly to a unique, high-efficiency hot water heater that satisfies space heating requirements, while simultaneously supplying domestic hot water in a single unit.
2. Background Art.
A typical, conventional hydronic space heating system is a closed hot water system in which hot water is circulated from a heater, or "boiler", to radiators in a building, which radiators transfer heat from the water to the surrounding air, with the now cooler water being returned to the heater. The heater typically includes a relatively small water reservoir heated by a relatively large burner fueled by either oil or gas. The system is usually controlled by a thermostat in the building which, when the temperature in the building falls to a predetermined level, causes the hot water in the reservoir to circulate through the finned devices. A second thermostat associated with the heater controls the burner to heat the water therein when it falls to a minimum temperature. Because the reservoir is small, resulting in a low quantity of heat storage, the burner must be of relatively large capacity, in order to meet the nearly instantaneous large heat demand.
In some systems, the burner cannot meet the instantaneous heat demand. Consequently, as cooler water returns to the reservoir from the radiators in the building, the temperature of the water in the reservoir drops and controls on the heater stop the flow of water through the system until the temperature of the water in the reservoir reaches a certain level. This cycling on and off of the water circulation means that the building will not be heated as rapidly as would otherwise be the case with a larger heated reservoir. Since most combustion systems must reach a certain temperature level before efficient operation is attained, the cycling on and off of the burner in such systems means that fuel is not as efficiently used as would otherwise be the case.
In the case of domestic hot water heaters, on the other hand, there is typically a relatively large reservoir of hot water heated by a relatively small burner. The result is that the burner cannot meet the instantaneous demand for hot water, but the large reservoir of hot water is usually, but not always, sufficient to supply ordinary demands. Because such heaters are frequently of low heating capacity, on the order, say, of 25,000 BTU per hour, it is not usually economical to construct them to be of high efficiency.
Accordingly, it is a principal object of the present invention to provide a combination heating unit which will provide both space heating requirements and domestic hot water requirements in a single unit.
It is another object of the present invention to provide such a combination heating unit that is compact and of high efficiency.
It is an additional object of the present invention to provide such a combination heating unit that is constructed to have a long service life.
Other objects of the present invention will in part be obvious and will in part appear hereinafter.